Fluorescent lighting provides an energy-efficient alternative to common incandescent lighting. However, the adoption of fluorescent lighting has been hindered in certain applications such as illuminating items in a retail setting. The quality of object color under fluorescent lighting is an important aspect of the value of the light source. Fluorescent lighting can produce visible light having muted light in the red region of the spectrum and an overemphasized amount of light in the yellow region. This lighting has been observed to produce cold or sterile light and light that generally washes out colors of the items being illuminated.
Incandescent lamps are known to generate significant light in the yellow region of the visible spectrum such as that produced by fluorescent lamps. One solution has been to filter out a portion of the yellow light with a glass envelope containing the rare earth element neodymium. An incandescent light bulb using neodymium doped glass is the REVEAL® bulb produced by GE. These bulbs depress light in the yellow region and thus have a greater red-green color contrast when compared with regular incandescent bulbs. As a result, consumers have found the enhanced color contrast light produced by the incandescent REVEAL® bulbs to be appealing. Thus, it would be desirable to develop light sources with enhanced color contrast similar to those achievable by neodymium glass-filtered incandescent sources. This has not heretofore been achievable for non-incandescent lamps.
Filtration with neodymium glass also tends to reduce the quantity of light produced by incandescent lamps. This disadvantage is acceptable due to the sufficient brightness of incandescent lamps. However, reduced lumen output in other lighting sources such as fluorescent lighting is less acceptable. There is a need for light sources other than incandescent lamps that generate enhanced color contrast without suffering from losing light output through filtering methods such as using neodymium glass.